It is conventional to make hollow plastic articles such as containers by closing a mold about a heated parison and blowing the parison outwardly against the confines of the mold to form the hollow article. Labels can be delivered to an open mold and deposited in the cavity of the mold so that, when the mold is closed and the parison is blown, the labels become adhered to and become a part of the blown hollow article. In U.S Pat No. 4,397,625, a reciprocating carriage is utilized to pick up labels from hoppers mounted on the frame of the blow molding machine and deliver them to the sections of the mold. Such an arrangement thus becomes a fixed part of the machine and provides for simultaneously delivering labels to both sections of the mold.
In certain types of machines, the space for delivery of the label into the open mold is limited because of the construction of the machine. More specifically, in one type of blow molding machine, a plurality of sets of molds are mounted on a wheel rotatable about a horizontal axis. The molds are movable toward and away from one another to enclose a parison, and the parison is then blown by application of air to the confines of the cavity between the mold sections as the wheel rotates. The blown articles are usually taken out of the blow molding machine at the twelve o'clock position and the extruded parison is introduced at the three o'clock position, such that the area during which the molds are open is limited. In such an arrangement, space is extremely limited, and the problem of placement of labels in the open mold is difficult. Where two labels are to be delivered for placement on opposite sides of the hollow article, the problem is more difficult. The problem is further complicated when the molds have plural cavities, and labels are to be delivered simultaneously to the plural cavities.
U.S. Pat. No. 4,680,000, assigned to the assignee hereof, discloses a method and apparatus for applying labels in the molds of a plastic blow molding machine in which labels are successively removed from one or more magazines, deposited on an endless conveyor that transports the labels to a position adjacent to an open mold, and laterally transferred from the conveyor to a position within the molds. When the mold closes about a plastic parison and the parison is blown, the labels become adhered to the blown plastic bottle. Although the technology disclosed in the noted patent has enjoyed substantial acceptance and success, further improvements remain desirable. For example, improvements are desirable in the pick-up arrangement for removing labels from the magazine and placing them on the conveyor. The pick-up mechanism of the noted patent includes a pair of spring-biased cam-operated linkage arms that undesirably expand due to centrifugal force during operation, and are difficult to control for removing labels from an angulated magazine and placing them on a continuously moving conveyor. Likewise, it is difficult to control motion of the inserter in the device of the noted patent accurately to remove labels from the conveyor and position them in the mold sections.